Electrostatic photocopy machine



Feb. 14, 1967 G c N ETAL ELECTROSTATIC PHOTOCOPY MACHINE 2 Sheets-Sheet 1' Filed May 4, 1964 L A m T G S m 0mm 0 C VF- NG 1R O E G ORIGINAL w W w. L a. a m V L w K N m F Feb. 14, 1967 G. c. KENT ET AL ELECTROSTATIC PHOTOCOPY MACHINE 2 Sheets-Sheet 2 Filed May 4, 1964 1, INVENTORS. Geonss C. KENT FRANKLIN R. Lswm:

mm tum United States Patent 3,303,763 ELECTROSTATIC PHOTOCQPY MACHINE George C. Kent, Highland Park, and Franklin R. Levine,

Elk Grove Village, Ilh, assignors to American Photocopy Equipment Company, Evanston, Ill., a corporation of Illinois Filed May 4, 1964, Ser. No. 364,698

Claims. (Cl. 951.7)

The present invention relates to an office photocopy machine of the electrostatic type and more particularly to an electrostatic photocopy machine capable of producing a superior result but at a substantially lower cost.

Electrostatic photocopy machines have fallen into two categories, the direct copy type in which the image is applied to a copy sheet made of specially coated paper and the indirect or offset type in which the image is applied to a photosensitive drum with subsequent development and transfer of the image to a sheet of ordinary noncoated paper. Both types of machines have tended to be elaborate and complex limiting usage to commercial establishments making a sufiicient number of copies to make the investment worthwhile, indeed, the cost of these machines has been so high as to encourage leasing rather than direct sale. In spite of the relativly high cost of existing electrostatic copying machines, they have not solved all of the practical problems inherent in the photocopy process and handling of the sheets, as, for example, the tendency of the original to creep or skew as it is recirculated to make multiple copies, and thus such machines have required service or adjustment from time tto time.

It is, accordingly, an object of the present invention to provide an electrostatic photocopy machine of the direct copying type which constitutes a departure from the usual design of such machines and in which the structure is exceedingly simple including a minimum number of moving parts and simplified control circuitry. It is another object to provide an electrostatic photocopy machine which is sufficiently low in cost and sufficiently light and compact as to permit usage in applications where the cost of a conventional electrostatic copying machine may not be justified, even usage for household purposes. In this connection it is an object to provide an electrostatic photocopy machine which requires only a fraction of the power normally required from an A.-C. supply line and which may be plugged in any conventional wall socket permitting the unit to be moved about at will and saving the cost of installing additional wiring.

It is another object to provide an electrostatic photocopy machine which is easy to operate and which includes a supply of copy sheets, self contained, and automatically fed into transport position simply upon insertion of the original into the machine.

It is still another object of the present invention to provide an electrostatic photocopy machine in which novel means are provided for holding the copy sheet and original for transport and exposure without recourse to elaborate guides and roller arrangements. In this connection it is an object to provide an electrostatic photocopy machine in which the original, while entrusted to the machine, is gently treated and which is capable of handling and protecting originals having a fragile backing, for example, thin tissue paper. It is a more specific object to provide an electrostatic photocopy machine in which the original and copy sheet, but particularly the original, are held in position on a drum or the like by electrostatic adherence. It is one of the features of the invention that multiple copies may be made simply by allowing the original to rotate a number of times on the drum to produce one copy per rotation but with complete 3,303,763 Patented Feb. 14, 1967 freedom from lateral creep or skew and, indeed, with the adherence being augmented each time the drum rotates.

In one of the aspects of the invention it is an object to provide a control arrangement for an electrostatic copying machine which produces automatic feeding of photocopy paper from the source of supply to a ready position and subsequently to an engaging position utilizing sheet actuated switches and without necessity for using relays or other relatively elaborate or expensive control elements.

It is yet another object of the invention to provide an electrostatic copying machine in which the original is supported tightly against an accurate reference surface during exposure permitting greater uniformity of focusing from one original to another and which does not require the original to be held in place by a glass window or other special positioning means required to engage the face of the sheet. Consequently a degree of optical precision is obtained which has not been obtained in office type photocopy machines to date.

Finally, it is an object of the invention to provide an electrostatic copying machine which secures an optimum condition of facing and transport in that the original is fed into the machine face up, copy sheets are stored in the machine face down for protection of the sensitive side during feeding to the transport elements, passed face up through a colloidal type developer and then discharged face up for instant and constant view by the operator until the desired number of copies have ben collected in the receiving tray,

Other objects and advantages of the invention will become apparent upon reading the attached detailed description and upon reference to the drawings in which:

FIGURE 1 is a perspective view, on a reduced scale, of a photocopy machine employing the features of the present invention.

FIG. 2 is a vertical section taken through the machine of FIG. 1.

FIG. 3 is a schematic diagram showing the control circuit of the machine.

FIG. 4 is a diagram showing use blanket.

FIG. 5 is a diagram showing a to the machine.

FIG. 6 is a fragmentary view showing a portion of the original drum 20 with the cooperating nip roller 25 and charging unit and showing use of a clamping sheet to clamp a relatively stiff original onto the drum surface.

While the invention has been described in connection with a preferred embodiment, it will be understood that we do not intend to be limited by the embodiment shown but intend to cover the various alternatives and equivalent constructions included within the spirit and scope of the appended claims.

Turning now to the drawings there is shown in FIG. 1 a machine 10 constructed in accordance with the invention and suitable for ofiice use. The machine includes a work table 11 having an entry slot 12 for feeding original documents into the machine together with lateral guides 13 which are adjustable in width and which serve to aline and center the original. Upon completion of the photocopy process, the original is discharged into a tray 15 which is included within the confines of the housing and which is readily accessible from the front of the machine. The completed copies collect in a lower tray 16. The machine is put into operation by an on-off switch 17 having an associated pilot light 18 and with a control button 19 which may be actuated where plural copies are desired.

For the purpose of transporting the original, which is placed upon the feed table 11 face up, a transport drum 20 is provided having a smooth cylindrical outer surface 21 and which is mounted for rotation on bearings 22. This of an insulating drum variably grounded drum extends from side to side within the housing of the machine and is of suflicient width to handle the originals which are to be fed into the machine and which, in the case of conventional oflice copies are 8 /2" in width. In rolling contact with the drum is a nip roller journaled in bearings 26 and which is preferably of resilient construction. Such a nip roller is preferably placed within a short distance of the inlet slot 12. As the original rotates around on the drum 20 in the direction indicated by the arrow, it passes an illuminating station 30 having a pair of lamps 31, 32. These lamps are preferably of the fluorescent type extending the length of the drum and are, as shown, located closely adjacent to the drum surface. The lamps are surrounded by longitudinal shields or housing members 33, 34 respectively which define a slit 35 defining a reading area. Direct escape of light from the lamps along the optical path is prevented by overlapping the shields with respect to the lamps. After passing the illuminating station the original is directed upwardly into a pair of spaced guide members 36, with the original being discharged by a pair of driven expeller rollers 37, 38 onto the return tray 15.

Turning attention next to the lower portion of the machine, means are provided for storing a stack of photocopy sheets and for feeding the sheets one by one by a separate feed motor which is controlled by the control circuitry to be discussed at a later point. For the details of construction of the feed motor and the associated feed elements, reference is made to Sacre Patent 3,126,122 which issued on Mar. 24, 1964. Briefly stated, a stack of sheets 40 is provided having a top sheet 41. In engagement with the top sheet is a rubber drive roller 42 which presses, by gravity or spring pressure, against the sheets and which is journaled in a pair of arms 43. The feed roller 42 is driven by a motor 45 with gears 46 completing the drive connection to the feed roller.

When the feed motor 45 is turned on, the top sheet 41 is driven through a pair of spaced guides 47 into a ready position 48, from which the sheet is transported, by further rotation of the motor, into engagement with a copy sheet drum 50. The copy sheet drum has a smooth outer surface 51 and is journaled within the housing on bearings 53. In rolling engagement with the drum adjacent the ready position 48, is a nip roller 55 which is resiliently surfaced and which is journaled in bearings 56. For the purpose of imparting an electrical charge to the surface of the sheet a corona unit is provided having a pair of longitudinally extending wires 71, 72 which are charged with high voltage from a high voltage power supply 73. The copy sheet carried by the copy sheet drum subsequently passes to an exposing station having a light shield 81 defining a transversely extending slot-like opening 85 which is similar in dimension to the slot 35 at the illuminating station. The copy sheet, after exposure, is stripped from the drum by a stripping blade 86 and is conducted by a guide 87 into engagement with drive rollers 88, 39 which conduct the exposed copy sheet to the developing apparatus.

In the present instance, the development takes place in a developing tank 90 having guiding edges 91 which engage the back of the sheet and which serve to direct the sheet through a body of developer fluid 92. The developer fluid is preferably a dielectric liquid having suspended therein a colloidal suspension of pigmented particles or toner which tend to adhere to the charged areas of the copy sheet thereby to develop the latent image acquired at the exposing station. From the developing tank 90, the sheet passes between a pair of squeegee rollers 95, 96 which are resiliently surfaced and biased together so that excess liquid runs back to the tray 90. From the squeegee rollers, which also act as expeller rollers, the sheet passes into a pair of guides 97 from which the sheet is discharged into the copy tray 16 previously referred to.

For the purpose of operating the drum and rollers at the same peripheral speed, they are interconnected by rubber timing belts, commonly referred to as cog belts, or the like. Thus the drive motor 100, which is preferably geared down to an output speed on the order of 20 r.p.m., has a belt 101 which drives the drum 5t} and which in turn is coupled, on a 1:1 ratio, by a belt 102-to the original drum 2th. The expeller rollers 37, 38 are driven from the latter by a belt 103. The drive rollers 88, 89 are, similarly, driven from the drum 5% by a belt 104. To complete the drive train, a belt 105, trained about the output pulley on the gear motor 100, serves to rotate the squeegee roller 96.

For the purpose of casting the image of the original upon the copy sheet with both original and copy sheet moving in unison, an optical reflecting element is used having a lens 111 and a mirror 112. The optical system is shielded against ambient light by a suitable optical housing 113. The optical path between the illuminating station and exposing station is indicated at 114. The light housing is preferably conical or trapezoidal to conform approximately to the optical path and to define upper and lower spaces 115, 116 for the trays 15, 16, respectively.

In accordance with the present invention, means are provided adjacent the nip roller at the input for imparting an electrical charge to the surface of the original, and the drum 20, on which the original is mounted, is made of a material which is capable of cooperating with the charge on the sheet so that the sheet is held to the drum by electrostatic force. In its simplest aspect the drum may be made of aluminum although other materials may be used without departing from the invention. Thus, adjacent the nip roller 25 we provide an auxiliary corona unit 129 having charged wires 121, 122 which are elec trically connected to the high voltage power supply 73. The charge applied to the surface of the original tends to distribute itself over the surface so that each unit area of the original becomes firmly adherent to the surface of the original drum. While additional corona units a may be used, it is found in practice that a single corona unit may s-uflice to impart the necessary attractive force to prevent the original from becoming free of the drum which carries it, particularly at the leading edge of the original, and to prevent lateral shifting as a result of repeated rotation of an original on the drum.

For the purpose of stripping off the original from the drum downstream :from the illuminating station, a stripper blade 125 is used which may extend the width of the drum and which is mounted :for limited swinging movement on a horizontally extending shaft 126. To rock the shaft 126, a crank 127 may be used connected by a suitable link 128 to the control knob 19. A spring 129 may be provided to bias the stripper blade 125 against the surface of the drum. When multiple copies are desired, the knob 19 may be pulled, thereby lifting the stripper blade from the drum and permitting the drum to recirculate as often as may be desired. The control panel at the front of the machine may be equipped with a tally device to serve as a convenient visual indication to the operator of the number of times that the original drum 20 is rotated with the same original.

In accordance with a related aspect of the present invention the electrical charge which is imparted to the copy sheet for photocopy punposes may be utilized for causing the copy sheet to adhere to the drum 50 which carries it. Thus the drum 50 may be made of metal just as in the case of drum 20, but to control the rate at which the charge is leaked off, the transport drum 50 is preferably provided with an insulating blanket 50a (FIG. 4) interposed between the surface of the drum and the copy sheet. This blanket may take various forms but for the sake of simplicity and to provide a compromise between adequate adherence and a good image, we prefer to use a layer of paper, for example, paper of the same type which is employed for the copy sheet itself but minus the sensitive coating. F or the :purpose of building up the charge in the surface of the copy sheet just prior to the time that it is exposed to the image of the original, we prefer to use an auxiliary charging unit 70a having charged wires 71a, 72a connected to the power supply 73.

In accordance with one of the aspects of the present invention, means are provided for maintaining a copy sheet in the ready position in readiness to be advanced into engagement with the transport drum 5i) when a copy sheet is required following insertion of an original into the machine. Thus referring to control circuitry in FIG. 3, we include in series with the feed motor 45 a normally closed switch 130 Which may be of the microswitch type having a feeler finger 131 which extends be tween the guides 47. Thus when power is initially applied to the machine by closing the switch 17, the feed motor 45 is energized rotating the rubber fee-d roller 42 and causing the top sheet 41 to be propelled upwardly between the guide members 47 until the leading edge of the sheet strikes the feeler finger 131 thus opening the switch 130 and turning off the feed motor.

Still :further in accordance with the invention means are provided for impulsing the feed motor for a sufiicient length of time, when the leading edge of the original reaches a predetermined point along its path of movement on the original drum 20, to incrementally advance the copy sheet into the copy sheet nip. Thus for the purpose of responding to the arrival of the leading edge at a reference position, indicated at 132, we provide a normally open switch 133 having a feeler finger 134. Arrival of the original at the point 132 closes the switch 133 turning on the feed motor 45. The latter is preferably capable of advancing a copy sheet at a rate which is several times the normal rate of transport within the machine. Thus where the peripheral speed of the drum 20, 50 is one inch per second, the feed mechanism may be designed for a speed of, say, ten inches per second. Thus the copy sheet is advanced from a ready position 48 over the short distance to the nip roller 55 within a time interval on the order of a fifth of a second. This insures that the leading edge of the copy sheet will be engaged in the nip in phase with the position of the original on the drum 20. Moreover, it is found that use of high velocity, into the nip, produces a slight impact and rebound at the nip, thus tending. to settle or square the leading edge of the copy sheet in the nip so that the sheet is more perfectly alined on the drum 50 which carries it. To prevent the feed motor 45 from operating after the copy sheet is engaged with the transport drum 50 a second, normally closed, switch which is provided on the down stream side of the switch 133 and slightly spaced therefrom. This switch, indicated at 135, has a feeler finger 136 which may, in a practical case, be located about a half inch or so from the finger 134. The effect is to turn on the feed motor 45 for a pulse of about a half seconds duration which is more than enough to advance the sheet from the ready position to the nip of the roller 55.

It is one of the features of the present machine that space normally wasted in the machine is effectively utilized for trays for receiving the original and copy sheets respectively. Thus instead of the optical housing 113, which is of conical shape, being at the back of the machine, as is conventional in machines of the electrostatic type, the housing is turned forwardly thereby defining a wedgeshaped space 115 in the upper portion of the machine for receiving an original and a wedge-shaped space 116, below the light housing, for collecting the copies.

While the operation of the device will be apparent from the above description, it willbe helpful to review this operation briefly. Thus when the switch 17 is turned on, turning on the main motor, power supply and pilot light, the normally closed switch 130 at the ready position 48 energizes the feed motor 45 causing the top sheet 41 to be driven through the guides 47 until the leading edge thereof strikes the finger 131 turning off the motor. An

original, face up on the worktable 11, is normally ad vanced into the entry slot 12 and into the nip of the roller 25. The roller 25, which is resiliently surfaced, tends to iron the sheet into contact with the surface of the roller and immediately thereafter the original passes under the corona unit 120 where it receives an electrostatic charge tending to cause the original to adhere tightly to the surface of the drum. When the original advances into engagement with the finger 134 of the switch 133 the circuit is closed to the feed motor causing the leading edge of the copy sheet 41 to advance at high speed from the ready position into the nip of the resilient roller associated With the transport drum, the feed motor being turned off a moment later by the normally closed switch 135. The copy sheet is ironed flat against the drum by the roller 55 and charged by the corona unit '70 which performs a dual function, namely, preparing the surface of the sheet for receiving the light image and for causing the sheet to adhere to the drum. Just prior to the copy sheet moving into the exposing station 80, the sheet may receive a supplemental charge from corona unit a.

Clearance of the switch 130 by the tail of the copy sheet serves to turn on the feed motor 45 again to advance the next copy sheet into ready position.

The original and copy sheet arrive at their respective stations in step with one another and the image of the moving original, passing along the optical path 114, is reflected back upon the surface of the copy sheet, selectively discharging the charge thereon and forming a latent image. The leading edge of the copy sheet is stripped off by a stripper blade 86 so that the sheet is directed between drive rollers 88, 89 and into the developer tray 90. Here the toner in collodial suspension, is deposited in the charged areas and the sheet passes upwardly into the nip of squeegee rollers 95, 96 which press out any excess liquid, expelling the developed copy sheet through the guides 97 into the receiving tray 16 where the copies are discharged face up. The original, after passing through the illuminating station, is stripped from the drum 20 and passes upwardly through the guides 36 into the tray 15 at the front of the machine.

Where multiple copies are desired, pulling out the multiple copy knob 19 lifts the stripper blade 125 from the drum 20 thereby permitting the original to recirculate. When the original in its second circuit strikes the finger 134 of the switch 133, the feed motor 45 is again energized so that the successive copy sheet in the ready position is advanced into the nip of the roller 55. Each time the original recirculates, the switch 133 serves to trigger the feeding of a copy sheet from the ready position into trans-port position and each time a sheet leaves the ready position it is promptly and automatically replaced by a new sheet from the stack.

Since the'original tightly adheres to the surface of the original drum 20, the original may be recirculated as often as desired without any tendency to creep laterally. Indeed, each time that the original is passed under the resilient nip roller 25 and each time the original acquires a charge from the corona unit it tends to adhere more tightly to the drum. Thus the recirculation feature for producing multiple copies is to be distinguished from conventional devices which employ a series of belts and rollers and the like and in which minor misadjustment as, for example, applying greater pressure at one end than the other, may cause progressive creep or skew of the original laterally within the machine with risk of damage to the margin of the original. In spite of the fact that substantial holding forces may be developed per unit area, the original may be readily lifted off by the stripping action of the blade 125. While a continuous stripper blade is preferred, extending the length of the drum, individual stripper elements may be used if desired having their tips recessed into grooves formed on the drum surface. Moreover, to improve the positiveness of 7 operation of the switches 133, 135, the fingers 134, 136 associated with the switches may be received in a shallow groove formed in the surface of the associated drum.

The construction described above has the advantage of high efiiciency combined with simplicity of both structure and function. Thus the multiple rollers usually required to conduct original and copy sheets in a photocopy machine may be dispensed with. Because of the lack of interfering structure, the illuminating lamps 31, 32 may be, as shown, mounted closely adjacent the drum 20, i.e., closely adjacent the reading area, in order to provide an extremely high level of illumination per watt of power consumed. The power consumption of the present machine is so low that the machine may be plugged into any ordinary wall socket. Because of this and because of the inherent compactness and light weight of the machine, it may be used as a portable and plugged in Wherever it is necessary to make copies. It will be appreciated by one skilled in the art that the control circuitry approaches the ultimate in simplicity making it unnecessary to use relays or other special control components which would add to the cost.

While a two drum machine has been described, it will be apparent to one skilled in the art that modifications may be made in the copy sheet transport without sacrifice of certain of the important features of the invention, for example, the charging of the original on the drum 20. Also while the automatic feed from a stack of sheets is one of the features of the invention as used in the present machine, it will be apparent to one skilled in the are that the invention is not limited thereto and that sheets may be hand fed to the transport means if desired.

Where it is desired to vary the characteristics of the resulting copy, the drum 50 which transports the copy sheet may be insulated from ground, for example by use of insulating bushings 14%) (FIG. 5), and may be grounded, instead, through a high resistance rheostat 141. Such rheostat may, for example, have a resistance within the range of 1 to 0-20 megohms. The effect of the resistance is to vary the leakage rate and hence vary the amount of charge which is on the copy sheet at the time that the sheet enters the exposing station as well as the electrostatic holding power. Consequently, use of a rheostat, permits a balance to be struck between the charge which is on the sheet for image purposes and the degree of holding force. Moreover, use of the rheostat 141 provides a convenient adjustment enabling optimum copying under various humidity conditions and in spite of minor variations in the composition or resistivity of the paper. The original drum may be similarly provided with an insulating blanket of plastic or the like, such as the blanket 50a (FIG. 4), and, if desired, insulating bushings 140 and a rheostat 141 (FIG. 5) to control adhesion under various ambient conditions.

The force holding the original to the drum 20 while adequate for all thicknesses of paper encountered in office usage may be augmented, where it is desired to use the machine for copying stiffer sheets, by employing an insulating clamping sheet of transparent plastic or the like which is placed on the top of and slightly in advance of the original as it is inserted into the machine. This sheet, which is indicated at 150 in FIG. 6, and which overlaps the leading edge of the original by a distance d, acquires an overall static charge, in this case positive, tending to attract the sheet to the drum with the original being clamped securely in between. The clamping sheet 150 is preferably made of Mylar or other dielectric material having a low leakage rate so that the charge remains on the surface of the clamping sheet throughout its circuit on the drum 20. Because of .the holding force at the leading edge, the leading edge of the original is constrained to follow the curvature of the drum 20 and there is no risk of the original being hung up within the machine. After the original has been exposed, the original and clamping sheets, together, are stripped from the drum and deposited in the tray 15 where the clamping sheet may be easily peeled off. The same technique may be used to project originals of a particularly fragile nature. As an alternative to using a transparent clamping sheet, a carrier may be used consisting of a sheet of the transparent material, folded at the leading edge to provide a double thickness and into which the original is slipped prior to being fed into the machine.

While the invention has been described in connection with a direct copy process in which the light image is formed directly on the final copy sheet, it will be ap parent to one skilled in the art that the invention in certain of its aspects, is applicable to the indirect electrostatic process in which the light image is cast uopn a charged selenium drum and developed on the drum before being offset upon, and fixed to a piece of paper. Consequently it will be understood that the term copy sheet will be understood to mean any sheet or surface capable of acquiring an electrostatic charge and having the characteristic of selective discharge in light struck areas to form a latent image for subsequent development by pigmented toner. For example, if desired, a selenium drum might be substituted for the transport drum 50 upon addition, to the lower pass of the drum, of a cloud chamber or the like for development purposes together with means for bringing a sheet of paper into contact with the drum for offsetting the developed image with subsequent cleaning by a brush or the like preparatory to the making of a successive cycle of rotation, in accordance with techniques well known in this art.

Also while we prefer to use a metal drum to carry the original, the term is not necessarily limited to a rigid drum but would include any member such as a belt having an extensive, generally cylindrical outer surface and capable of electrostatic adherence of the original to be copied.

We claim:

1. In an electrostatic photocopy machine the combination comprising a frame, an original drum and a copy sheet drum together with means for rotating them at the same peripheral speed, nip rollers associated with said drums for aligning and pressing the original and copy sheet against the surface of the respective drums, a source of copy sheets in the frame, means for feeding an original to the nip of the original drum, means for feeding a copy sheet to a ready position just short of the nip of the copy sheet drum, illuminating and exposing stations associated with the drums respectively and optically coupled together for the casting of the image of the original on the copy sheet, means triggered by the arrival of the leading edge of the original for advancing a copy sheet from the ready position to the nip of the copy sheet drum so that the original and copy sheet arrive at the illuminating and exposing stations in step with one another, means for developing thecopy sheet, and means for discharging the original and copy sheet from the machine, said original drum having means for imparting an electrostatic charge to the original at the output of the original drum nip for achieving adherence of the original and said copy sheet drum having means for imparting an electrostatic charge to the copy sheet at the output of the copy sheet drum nip for preparing the copy sheet for receiving the image and for achieving adherence of the copy sheet.

2. In an electrostatic photocopy machine the combination comprising a frame, an original drum and a copy sheet drum, means for rotating the drums at the same peripheral speed, means for feeding an original onto the surface of the original drum and a copy sheet onto the surface of the copy sheet drum, a supply of copy sheets in the frame, a sheet feeder interposed between the supply and the copy sheet drum, illuminating and exposing stations associated with the original drum and the copy sheet drum respectively and optically coupled to one another for the casting of the image of the moving original on the moving copy sheet, means associated with the original drum for imparting an electrostatic charge for achieving adherence of the original and means associated with the copy sheet drum for imparting an electrostatic charge for preparing the copy sheet for receiving the image and for achieving adherence of the copy sheet, a switch at the surface of the original drum and actuated by the leading edge of the original thereon for triggering the feeding means so that the original and copy sheet arrive at the illuminating and exposing stations, respectively, at the same time so that the copy sheet acquires the image of the original, means for developing the copy sheet, and means for discharging the original and developed copy sheet from the machine.

3. In an electric photocopy machine the combination comprising a frame, means for feeding and transporting an original, a cylindrical drum having rotation means synchronized with the movement of the original, said transport means having an illuminating station and said drum having an exposing station, means for optically associating the illuminating station and the exposing station so that the image of the moving original is cast upon the moving copy sheet, means for developing the image, said drum having a resilient roller engaging the same to provide a nip for aligning and for pressing the copy sheet against the surface of the drum and having immediately adjacent said roller and before the exposing station a charging device for imparting an electrostatic charge to the copy sheet for preparing the copy sheet for receiving the image and for achieving adherence to the drum, and means for stripping the copy sheet from the drum.

4. In an electrostatic photocopy machine the combination comprising a frame, an original drum and a copy sheet drum, means for rotating the drum at the same peripheral speed, means for feeding an original onto the surface of the original drum and a copy sheet onto the surface of the copy sheet drum, said original drum having an illuminating station and said copy sheet drum having an exposing station, means for optically associating the illuminating station and exposing station so that the image of the moving original is cast upon the moving copy sheet, means for developing the image, said drums each having resilient rollers engaging the same to provide a nip for aligning and pressing the original and copy sheet against the surface of the respective drums, said original drum having means for imparting an electrostatic charge to the rginal immediately adjacent said original drum roller for achieving adherence to the original drum and said copy sheet drum having means for imparting an electrostatic charge to the copy sheet immediately adjacent said copy sheet drum roller and before the exposing station for preparing the copy sheet for receiving the image and for achieving adherence to the copy sheet drum.

5. In an electrostatic photocopying machine having means for transporting an original and a copy sheet, an illuminating station for the original sheet and an exposing station for the copy sheet, With both stations optically related to one another together for the casting of the image of the moving original on the moving copy sheet and means for developing the image, the suhcombination of an original drum in the transport path of the original and a copy sheet drum in the transport path of the copy sheet, resilient rollers engaging each of the drums for aligning and pressing the original and copy sheet against the surface of the respective drums, an electrostatic charging device associated with the original drum located adjacent said original drum roller for achieving adherence of the original and an electrostatic charging device located adjacent said copy sheet drum roller for preparing the copy sheet for receiving the image and for achieving adherence of the copy sheet.

References Cited by the Examiner UNITED STATES PATENTS 3,033,095 5/1962 Lirnberger -775 3,092,005 6/ 1963 Limberger 9575 3,099,856 8/1963 Eichorn 95-1.7 X 3,152,528 10/1964 Pendry 951.7 3,174,748 3/1965 Roberts 2718 3,207,050 9/1965 Limberger 95l.7 3,221,621 12/1965 Cranskens 95-1,7

JOHN M. HORAN, Primary Examiner. 

1. IN AN ELECTROSTATIC PHOTOCOPY MACHINE THE COMBINATION COMPRISING A FRAME, AN ORIGINAL DRUM AND A COPY SHEET DRUM TOGETHER WITH MEANS FOR ROTATING THEM AT THE SAME PERIPHERAL SPEED, NIP ROLLERS ASSOCIATED WITH SAID DRUMS FOR ALIGNING AND PRESSING THE ORIGINAL AND COPY SHEET AGAINST THE SURFACE OF THE RESPECTIVE DRUMS, A SOURCE OF COPY SHEETS IN THE FRAME, MEANS FOR FEEDING AN ORIGINAL TO THE NIP OF THE ORIGINAL DRUM, MEANS FOR FEEDING A COPY SHEET TO A READY POSITION JUST SHORT OF THE NIP OF THE COPY SHEET DRUM, ILLUMINATING AND EXPOSING STATIONS ASSOCIATED WITH THE DRUMS RESPECTIVELY AND OPTICALLY COUPLED TOGETHER FOR THE CASTING OF THE IMAGE OF THE ORIGINAL ON THE COPY SHEET, MEANS TRIGGERED BY THE ARRIVAL OF THE LEADING EDGE OF THE ORIGINAL FOR ADVANCING A COPY SHEET FROM THE READY POSITION TO THE NIP OF THE COPY SHEET DRUM SO THAT THE ORIGINAL AND COPY SHEET ARRIVE AT THE ILLUMINATING AND EXPOSING STATIONS IN STEP WITH ONE ANOTHER, MEANS FOR DEVELOPING THE COPY SHEET, AND MEANS FOR DISCHARGING THE ORIGINAL AND COPY SHEET FROM THE MACHINE, SAID ORIGINAL DRUM HAVING MEANS FOR IMPARTING AN ELECTROSTATIC CHARGE TO THE ORIGINAL AT THE OUTPUT OF THE ORIGINAL DRUM NIP FOR ACHIEVING ADHERENCE OF THE ORIGINAL AND SAID COPY SHEET DRUM HAVING MEANS FOR IMPARTING AN ELECTROSTATIC CHARGE TO THE COPY SHEET AT THE OUTPUT OF THE COPY SHEET DRUM NIP FOR PREPARING THE COPY SHEET FOR RECEIVING THE IMAGE AND FOR ACHIEVING ADHERENCE OF THE COPY SHEET. 